Per Pentaxforums.com the K7 has a guide number of 13 meters and the KP has a guide number of 6 meters.
The inverse square law applies.
The K7's flash provides appoximately 4.7 times more light output than the KP.
I had a similar problem with the Godox flash I attached to my d7500. It turns out that the contacts on both the flash and the hot shoe were dirty enough to cause a problem. A few seconds of light burnishing with some very fine steel wool solved it--taking care to blow away the residual dust and debris. I wouldn't do this every day, but if you leave the ...